Diesel engines frequently utilize spin-on filters which have stacked filter elements wherein one filter element is a full-flow filter element and the other filter element is a bypass flow element. With such filters, two distinct flow paths are channeled through two stacked filter elements within a spin-on filter. The full-flow path removes large particles and supplies the system with lubricating oil while the bypass flow path provides a low efficiency loop which returns filtered lubricant to a storage sump. The resulting arrangement provides lubricating oil with an improved overall cleanliness.
In prior art approaches, separating the flow paths requires use of lathe-cut gaskets, O-rings, grommets, molded components, metal tubes with welded or press fit subassemblies, and unique end caps in order to provide sealing surfaces for separation of the full-flow and bypass flow paths. Generally, the molded components of these assemblies are configured so as to require mechanical support and centering assistance from specially designed end caps. In practice, tooling for two to three end cap configurations are necessary, each of which is useless in dissimilar applications. Moreover, the alignment of stacked filters during production is a relatively difficult task and utilizing solid center tubes with welded subassemblies are required to facilitate the design. These aspects of prior art filter assemblies result in relatively high material and labor costs, and in addition, keep the length of time required for production relatively high.
In view of these considerations, there is a need for an arrangement which utilizes standardized components such as standardized end caps, element supports and inner element structures. Moreover, there is a need for a construction which is self-centering, eliminating the need for unique end cap configurations, and there is a need for an arrangement which does not require mechanical support from a lower end cap. Solving these problems results in reduced labor costs and tooling costs and a reduction in the total number of inventoried parts required for each dual-flow lubricating filter assembly.